Bacterin That Induces Anti-OspA and Anti-OspC Borreliacidal Antibodies Provides a High Level of Protection against Canine Lyme Disease

Abstract

Groups of 15 laboratory-bred beagles were vaccinated and boosted with either a placebo or adjuvanted bivalent bacterin comprised of a traditional Borrelia burgdorferi strain and a unique ospA- and ospB-negative B. burgdorferi strain that expressed high levels of OspC and then challenged with B. burgdorferi-infected Ixodes scapularis ticks. The vaccinated dogs produced high titers of anti-OspA and anti-OspC borreliacidal antibodies, including borreliacidal antibodies specific for an epitope within the last seven amino acids at the OspC carboxy terminus (termed OspC7) that was conserved among pathogenic Borrelia genospecies. In addition, spirochetes were eliminated from the infected ticks that fed on the bacterin recipients, B. burgdorferi was not isolated from the skin or joints, and antibody responses associated specifically with canine infection with B. burgdorferi were not produced. In contrast, B. burgdorferi was recovered from engorged ticks that fed on 13 (87%) placebo-vaccinated dogs (P<0.0001), skin biopsy specimens from 14 (93%) dogs (P<0.0001), and joint tissue specimens from 8 (53%) dogs (P=0.0022). In addition, 14 (93%) dogs developed specific antibody responses against B. burgdorferi proteins, including 11 (73%) with C6 peptide antibodies (P<0.0001). Moreover, 10 (67%) dogs developed Lyme disease-associated joint abnormalities (P<0.0001), including 4 (27%) dogs that developed joint stiffness or lameness and 6 (40%) that developed chronic joint inflammation (synovitis). The results therefore confirmed that the bacterin provided a high level of protection against Lyme disease shortly after immunization.

Synovial Lesions in Experimental Canine Lyme Borreliosis

“…Infection with B. burgdorferi was confirmed in tick-exposed dogs by culture and PCR testing of skin punch biopsies taken at 83 dpi as previously described, 7,14,27 as well as by ELISA, as this was sufficient time to induce an immunoglobulin G antibody response. 2 Before humane euthanasia, serum samples were obtained for testing for antibodies to B. burgdorferi, Anaplasma phagocytophilum, Dirofilaria immitis, and Ehrlichia canis with a commercial kit (C6 SNAP 4Dx, Idexx Laboratories, Westbrook, Maine).…”

“…Twelve male and 13 female ticks were placed on clipped skin of the left shoulder in a secured plastic capsule as previously described. 2,14,30 Ticks were allowed to feed until detachment (about 4 to 7 days). Animals were euthanized, and necropsy examinations were performed at 90 days postinfection (dpi) (3 exposed and 1 control dogs), 120 dpi (3 exposed and 1 control), and 190 dpi (12 exposed, 2 controls).…”

Antibody responses toBorrelia burgdorferiouter surface proteins C and F in experimentally infected Beagle dogs

“…Archived serum samples from 24 healthy laboratory purpose-bred Beagles that had received only placebo prior to challenge with B. burgdorferi-infected ticks in previous studies 3,4 were then evaluated. The dogs were challenged by attaching 10 female and 10 male B. burgdorferi-infected I. scapularis ticks and allowing the female ticks to feed to repletion.…”

“…The mean of the resultant optical density (OD) values was then calculated, and OD values ≥2 standard deviations (SDs) above the mean were considered significant. The appropriate positive controls were then identified by testing serial 2-fold dilutions of a dog serum that contained a high level of anti-OspC antibodies induced by vaccination against Lyme disease 4 and a human Lyme disease serum that contained a high level of anti-OspF antibodies. The minimum amount (last dilution) of serum necessary to yield significant (OD ≥ 2 SD above mean of normal dog sera) reactivity was then determined.…”

“…The plates were then re-incubated, washed, and o-phenylenediamine substrate b was used to detect bound antibodies. The reactions were stopped by adding 1 N H 2 SO 4 , and the absorbances at 490 nm i were determined immediately. We subsequently established the significant reactivity cutoff values for each ELISA by testing non-Lyme disease (normal) sera (n = 72) from client-owned dogs in Wisconsin (n = 15), New Hampshire (n = 44), and New York (n = 13) with no prior clinical or serologic (tested using a commercial assay j ) evidence of infection with B. burgdorferi or suspicion of tick exposure (e.g., city and/or house dogs).…”